Description of the Prior Art
There are various types of engines which are classified based on the arrangement of their cylinders, such as engines with cylinders connected in-line, engines with cylinders connected in opposed states, V-shaped engines, etc.
In V-engine constructions, the first and second cylinder heads are placed on the upper surface portions of a V-shaped cylinder block, thereby forming first and second cylinder banks arranged in a V-shape.
A space or open zone, hereinafter sometimes referred to as the "V-bank space", is formed between the first and second cylinder banks forming the upper part of the V-engine, and an intake manifold is disposed in this space.
Further, as a cooling water system for a V-engine, there is disclosed in Japanese Utility Model Laid-open Publication No. Sho 62-91615, a system in which a water pump is adapted to feed cooling water to water jackets formed on each of a pair of banks of a V-engine. The pump is disposed on one side, in the crankshaft directions of the pair of banks, in such a manner that an intake port of the pump faces the V-bank space. A collecting pipe adapted to receive cooling water from the water jackets and feed same toward the radiator is disposed on the other side in the crankshaft directions of the banks. The collecting pipe is integrally formed with a valve casing adapted to accommodate therein a thermovalve which is mounted on the downstream side of the radiator such that an outlet port of the casing faces toward the V-bank space side. A connecting valve adapted to interconnect the outlet port and the inlet port is disposed within the V-bank space.
In a cooling water system of a conventional V-engine, as shown in FIG. 8, a plurality of branch pipes 124 of an intake manifold 120, which manifold is disposed in the V-bank space portion 114 of a V-engine 102, are disposed in such a manner as to extend perpendicularly to the centerline A of the V-engine 102. Owing to the foregoing arrangement, the cooling water intake pipe 126 and the cooling water discharging pipe 128 cannot be disposed within the space portion 114; rather the cooling water intake pipe 126 and the cooling water discharging pipe 128 are formed as separate bodies, respectively, the cooling water intake pipe 126 being extended from an intermediate part of one longitudinal end (left-hand side in FIG. 8) of the V-engine 102 toward one vertical side (upper side in FIG. 8) thereof, the cooling water discharging pipe 128 being extended from the other longitudinal end (right-hand side in FIG. 8) portion to the first-named longitudinal end (left-hand side in FIG. 8) of the V-engine 102 via the other vertical side (lower side in FIG. 8) of the V-engine 102.
As a result, the cooling water discharging pipe 128 extends through the outside portion from the V-engine 102 and the size of the V-engine is thereby increased, which is disadvantageous in practical use. In addition, the appearance of the V-engine is degraded.
Further, since the cooling water intake pipe 126 and the cooling water discharging pipe 128 must be manufactured as separate bodies, the manufacturing costs of the cooling water intake pipe 126 and the cooling water discharging pipe 128 are increased, which is economically disadvantageous.
When the V-engine is of the type that is placed in a vertical state and used in a FR (front engine/rear drive) vehicle, it is difficult to obtain sufficient space for installing cooling water pipes, such as the cooling water intake pipe, the thermohousing, the cooling water discharging pipe, etc. within the space that is formed between a pair of the inclined cylinder banks.
That is, in a vertical V-engine, a radiator is separately disposed in the front part of the cylinder block and the water pump is also disposed in the front part of the cylinder block. Cooling water is introduced into the water pump through the cooling water intake pipe which is connected with the radiator and then the cooling water is caused to flow into the pair of cylinder heads from the cylinder block. Then, it is flowed into a collecting pipe disposed at the rear part (transmission side) of the cylinder block via each of the cylinder heads and is returned to the radiator disposed at the front part of the cylinder block through the cooling water discharging pipe that communicates with the collecting portion.
However, an intake manifold is located in the space portion formed between the cylinder banks of the V-engine. This intake manifold is disposed close to the cylinder block in such a manner that its pair of side surge tanks, which communicate with the pair of cylinder heads through side branch pipes, are located at the lower part of the space.
Because of the foregoing arrangement, it was difficult to obtain space for installing therein the thermohousing which is mounted on the cooling water intake pipe and the cooling water discharging pipe communicating with the collecting pipe within the space formed between the cylinder banks.
The cooling water discharging pipe can be disposed at the outside of the cylinder block in such a manner as to extend in the crankshaft direction or the cooling water intake pipe can be disposed in a space at a lower part of an intake manifold as disclosed in the above-mentioned publication.
However, the arrangement for disposing the cooling water discharging pipe at the outside of the cylinder block has the inconveniences that since the cooling water intake pipe must be separately disposed, the cooling water pipings must be manufactured as separate bodies, the cost and weight thereof are increased, a compact structure is not obtainable, and the appearance is degraded.
When a cooling water intake pipe is disposed in a space at a lower part of the intake manifold, as disclosed in the above-mentioned publication, the structure can be made compact to some extent. However, in this publication, since the thermohousing is disposed in such a manner as to project outwardly from the collecting pipe and the cooling water discharging pipe is disposed at the outside of the cylinder block, it is difficult to make the whole structure sufficiently compact and, in addition, the appearance is degraded. Further, in this publication, in order to avoid interference between the end portion of the cylinder block on the other side in the crankshaft direction and the surge tank and the communicating portion with respect to the collecting pipe of the cooling water intake pipe, the cooling water intake pipe is required to be disposed in such a manner as to be separated upwardly away from the cylinder block. This means that the installation space for the intake manifold is reduced. As a result, there are the inconveniences that because the intake manifold projects outwardly from the space formed between the side cylinder banks, the structure cannot be compact and the capacity of the surge tank disposed at the intake manifold is reduced.
In the V-engine, as shown in FIG. 9, first and second cylinder heads 310-1, 310-2 and first and second cylinder head covers 312-1, 312-2 are placed on upper surface portions of a V-shaped cylinder block 304, respectively, thereby forming first and second cylinder banks 314-1, 314-2 in a V-shape.
A space 316 is formed between the first and second cylinder banks 314-1, 314-2 at the upper part of the V-engine 302, and an intake manifold (not shown) and an auxiliary apparatus disposed across the first and second cylinder heads 310-1, 310-2 are arranged in this space.
As a structure for arranging auxiliary apparatus in a V-engine, Japanese Utility Model Early Laid-open Publication No. Sho 62-84635 discloses one which is designed such that in a V-engine, a crank pulley is mounted on an outer side of one end of an engine body in the crankshaft direction thereof and a transmission casing is mounted on the outer side of the other end thereof. An intake manifold is disposed in the space which is formed between the pair of banks of the engine body. The intake manifold, with a throttle body mounted thereon expanded toward an upper space of the transmission casing, is disposed in such a manner as to be extend toward the transmission casing in the V-bank space in order to form a space, on the crank pulley side, where no intake manifold is present. An auxiliary apparatus driven through the crank pulley is disposed in this space.
Furthermore, there is disclosed in Japanese Utility Model Early Laid-open Publication No. Sho 62-69034, a V-engine comprising two sets of cylinder rows formed by arranging individual cylinders in series and connected in a V-shape at a predetermined bank angle. An auxiliary machine part, including a driven pulley, is disposed in the V-valley portion and is accommodated in the center of an upper side of the cylinder block which accommodate the two sets of cylinder rows. The driven pulley is driven by the crankshaft through a belt drive system.
In the conventional structure of an auxiliary apparatus for a V-engine, as shown in FIG. 9, a generator 344 as an auxiliary apparatus is disposed in the space 316 of the V-engine 302 such that the center C1 of the V-engine 302 and the center C2 of the generator 344 are vertically aligned, that is, they both lie in the same imaginary vertical plane.
A cooling water pipe 342 is disposed in the vicinity of the intake manifold on both sides of the V-engine 302 in such a fashion as to project outward.
As a result, when the V-engine 302 is driven, the cooling water pipe 342 is heated by the heat of an exhaust manifold 356 and the cooling efficiency of the cooling water is lowered, which is inconvenient in practical use.
To avoid the above inconvenience, there was encountered another inconvenience in that the radiator (not shown) must be made large in size.
Further, since the generator, as an auxiliary apparatus, is disposed in the space 316 of the V-engine 302 in order to bring the center of the V-engine 302 to be coincident with the center of the generator 344, it is impossible to use this space 316 efficiently to lay out other auxiliary machines therein, which is disadvantageous in practical use.
Furthermore, since the cooling water pipe 342 projects outwardly when the V-engine 302 is mounted, there was the additional inconvenience that the workability of the mounting operation of the V-engine 302 was diminished and the cooling water pipe 342 is likely to get damaged, which is disadvantageous in practical use.